First thing to remember is that all courier companies, all postmen, all delivery service people, do not handle a heavy package like yours containing a loudspeaker with kid gloves. If it is heavy the delivery driver will slam it down on the ground. In fact he will take some macho pride in doing this. Look how heavy this is - being carried by me! - slam down it goes! (That will impress the girls). It won't impress the person who bought the speaker to find the frame all bent out shape though. You can guarantee that if the buyer laid down good money for a hefty speaker, he wants to see good packaging to protect it. So take good time to get the packing right, or there will be sorry faces, and it won't be the delivery company that pays up.
The second thing to bear in mind is that when you buy a new speaker from your local dealer, it comes in a specially designed box. But don't believe for one moment that this is there to protect the speaker. Sure, it needs a box when it is on your dealer's shelf, and a lot of these boxes are all nicely presented - but that is exactly what they are, just presentation boxes, and they won't do for posting. Ask yourself, have you ever seen an address label on the side of one of these boxes you got from the dealer? No you haven't, and that is because these boxes are packed into a larger crate with a hell of a lot of foam and air bags around them to protect them. All speakers are sent double boxed!
So in order to correctly pack up your speaker this is what you should aim to do. Firstly find a good close fitting sturdy cardboard box that is just about the size of your speaker. The box doesn't need to be the neatest looking thing on earth, just make sure it fits closely around your speaker to prevent it rattling around too much. (you can cut back a larger box to make a better fit). Into this box goes the speaker, WITHOUT ANY FOAM OR PACKING MATERIAL. What you are trying to acheive is a shell to protect your speaker from impact , (and that includes the shock of an impact being transmitted through any packing material, and the effect of gravity causing the speaker to move in the opposite direction). Right, now you have the first box, go and find a larger box that will accommodate the first with plenty of room to spare. Thats right, you need two boxes. You put the speaker in the smaller close-fitting box and tape it up. Then you put this box into the larger box, placing it onto a cushion of expanded foam or bubble wrap, or some other soft impact absorbing material. Put more bubblewrap in all the gaps in the space in between the two boxes, and then close the lid. Tape-up with plenty of parcel tape so the whole thing is secure and there you have it - ready to send!
please note that:
1) the most likely case of damage to a speaker driver is an impact to the magnet. This is the heavy side which the courier will naturally put face down when lifting - and so this is going to be the first thing to hit the ground. Make sure there is lots of padding between the magnet side and the outside box. A blow to the magnet is likely to cause a fractional bend in the frame - not enough to see, but enough to trap the voice coil on your speaker and render it useless.
2) you don't want any foam or packing material in a place where it can come into contact with the paper cone of the speaker. A lot of people drop an unguarded speaker into a box full of foam chips thinking that will make a nice cushion. It won't!! The chips will press against the paper of the cone and cause it to go out of shape, or worse, the pressure will detatch the paper rim from the metal frame. Think always, the paper is delicate, and the frame and magnet is very heavy - don't have the weight of the magnet working against the paper.
3) an effective way of packing two speakers is to pair them up face to face. Bolt them together - never use wire or nylon cable ties as these are not strong enough to prevent the heavy speakers shifting about. Slight movement will have a shearing action on cable ties and they will break; you will then have two heavy speakers moving around freely and slicing into one another's cone. Remember bolts only for face-to-face. Don't put any more than two speakers in one inner box. If many speakers are going into a larger crate then think about how you position them - no two magnets should be close enough to hit against the other and cause impact damage.
4) The best form of padding is bubble-wrap or the softer type of expanded foam. Hard styrofoam blocks are not so good as these have a tendancy to transmit the force of impact. If you must use hard styrofoam, then break it up into smaller chucks, and don't blame me if you front room looks like it got hit by a snowstorm.
If this is too much trouble then you might consider the option of collection for your speaker. You might be surprised just how many people are willing to travel just to get their hands on the right loudspeaker for their hifi or guitar amp. So always offer that as an option. It may even save you time in the long run as you don't need to wrap the thing up, just put it in a box and thats fine!
When things go wrong:
loose speakers can really wreck themselves. This is what happens when you put two heavy speakers in an inadequate box and tie them together with a piece of USB cable.
Thinking inside the box. OK lets have a look:
Not much packing material. Chunks of polystyrene pressed up against the paper cone:
and the two speakers free to move about and grind into one another:
The end result - one speaker with coil rub possibly after a knock to the magnet, and the other with a rattle in the back and indentations in the paper cone, caused by the USB cable getting between the gap. The speakers were very cheap, but the seller charged a premium price for delivery, which, given the service received, kinda sucks.